The invention relates to a sterilization system, more particularly to a system for treating, sterilizing and burning a wide variety of toxic and infectious wastes within a completely closed system.
Health and environmental concerns have driven a search for sterilization and decontamination systems capable of efficiently sterilizing and destroying toxic waste without emitting the toxins into the outside environment. This is particularly true in the hospital environment where waste materials may carry highly infectious viruses such as the aids virus, which require the isolation, sterilization and incineration of these materials to avoid further contamination. Traditional sterilization systems which process and sterilize waste with a well known sterilizing medium such as germicidal sprays, tend to emit unacceptable amounts of toxins since the toxic waste is not effectively sealed within the treatment system and the sterilized waste is not prevented from commingling with the untreated waste. In addition, the burners normally located at the back end of the sterilizing medium tend to burn waste at relatively low temperatures thereby emitting unacceptably high levels of toxic fly ash and other pollutants.
Although some attempts have been made to sterilize thoroughly and incinerate toxic waste, these systems have proven ineffective in completely isolating and sterilizing the waste materials. For example, U.S. Pat. No. 4,185,973, which issued to Tester on Jan. 29, 1980, discloses a waste disposal system (eg. for a hospital), in which a series of shredders 2 pulverize the waste material. The pulverized waste is then drawn by air suction through a closed ducting system 53,54,56,58 for destruction. Each shredder has a discharge valve 66 positioned in the waste outlet which partly closes off the remainder of the system from the associated shredder when the waste input of the latter is open. This system while being an improvement over earlier systems by partially sealing the toxic waste from the sterile waste, is still deficient since it is arranged to provide incomplete sealing so that a small amount of air flows into the associated shredder. The shredder also has a vent opening in its waste inlet door to relieve pressure, as well as internal germicidal sprays. Furthermore, this system is not conducive to handling highly infectious waste material, since most germicidal sprays fail to sufficiently sterilize this type of highly toxic material thereby resulting in toxins being emitted in the environment during the combustion process.
U.S. Pat. No. 4,250,139 to Luck discloses a method for decontaminating proteinaceous host materials from microorganisms, while retaining the chemical, physical and physiological properties of the proteinaceous host materials. The method comprises dehydrating the host material and then subjecting it to lethal doses of microwave energy at ambient temperature. Although Luck discloses the broad concept of utilizing microwave energy as a more effective sterilizing medium, this system could not be used to treat toxic waste having a high moisture content since there are no provisions in this system for uniformly heating and treating waste material of varying moisture levels.
U.S. Pat. No. 4,037,795 issued to Fyfe discloses a centralized vacuum waste disposal system, particularly for use in hospitals. The system includes a shredder 10 which feeds into a remote incinerator via a ducting system 17,18,27. A set of air compressors 24,26 maintains a continuous upstream pressure substantially below atmospheric pressure to draw air carrying the pulverized waste through the ducting. To prevent contaminated air from escaping from the system if the compressor stops running, an auxiliary device is provided to maintain a partial vacuum at all times. This system lacks any highly efficient sterilizing medium.
U.S. Pat. No. 3,922,975 issued to Reese discloses a method and apparatus for feeding solid waste to a fluid bed disposal apparatus. The combustion assembly includes the waste delivery assembly 10 where solid waste material is collected, shredded and separated for introduction into the combustion assembly. In the combustion assembly 50, the solid waste is consumed and can also serve as a fuel to dispose of sludge. The combustion gas particle cleanup assembly 90 removes entrained particles from the combustion gases which are then either exhausted of conveyed on to perform work. An air lock feed valve 35 introduces the solid waste into a fluid conduit 36 where the material is pneumatically conveyed into the fluid bed.
This system, like the Fyfe system lacks any effective sterilizing medium for highly infectious waste or any isolator arrangement at the front and back end of the treatment step to ensure that the treated waste remains isolated from the untreated waste. Thus, the current art fails to disclose a closed sterilization system which economically and efficiently sterilizes toxic waste, while sealing the untreated toxic waste away from the treated waste.